A strange algae plume has turned the normally crystal clear Caribbean Sea around the Virgin Islands green down to a depth of roughly 80 feet (25 metres) and sharply decreased visibility in these popular dive waters. How and if the plume will have any long-term effect on the region’s marine life remains unknown.

Tyler Smith, assistant professor at the Center for Marine and Environmental Studies at the University of the Virgin Islands, said that when he went diving Tuesday the visibility inside the plume was no more than 10 feet (3 metres). Below 80 feet, the water was just as clear as normally.

The reason behind the extraordinary plume can be found in South America, in the Orinoco River which flows through Venezuela before reaching the Atlantic Ocean. When the Orinoco outflow is larger than normal, the vast amounts of nutrient-rich freshwater from Venezuela cause a major algae bloom in the nearby ocean. Mixed fresh- and saltwater is lighter than seawater and will therefore rise to the top of the water column.

“It’s very stable, so it just sits there,” Smith explains.

Carried by currents, the algae plume has now spread from the South American east-coast to the Caribbean Sea and can currently be seen not only off the British and U.S. Virgin Islands but in Puerto Rican waters as well. The first patch was noticed by Smith and his colleagues in the waters off St. Croix on April 9.

When the amount of photosynthesising alga increases in a region, it attracts all sorts of organisms that feed on algae and make it possible for these populations to boom as well. The algae plume around the Virgin Islands supports an entire food chain of marine life, including plankton, jellyfish, crustaceans and fish. It is not dangerous to swim or scuba dive in, but some people might dislike the high density of jellyfish.

“This is an event that occurs every year, but we haven’t seen it come this far north,” says Trika Gerard, marine ecologist with the U.S. National Oceanic and Atmospheric Administration (NOAA). In a stroke of good luck, a NOAA research vessel was scheduled to research reef fish in these waters from April 7 to April 20 – right at the peak of the unexpected plume.

To find out more about how the plume effects marine life, the Caribbean Fisheries Management Council is urging anyone who goes out fishing in the green plume to report their location, target species and success rate of each trip. According to local fishermen the fishing is always awfully bad when the water is green, but this has not been scientifically researched yet and all data is of interest.

You can reach the Caribbean Fisheries Management Council by calling (787) 766-5927. Their website is http://www.caribbeanfmc.com.

A new species of ghost knifefish has been described by ichthyologists James Albert and William Crampton. It has been given the name Compsaraia samueli in honour of Samuel Albert who presented the scientists with the type specimens.

Ghost knifefish (family Apteronotidae) are famous for their body shape and for using a high frequency tone-type electric organ discharge (EOD) to communicate. The native home of these fishes are South and Central America. Within the aquarium hobby, the Black ghost knifefish (Apteronotus albifrons) and Brown ghost knifefish (Apteronotus leptorhynchus) are fairly common.

Samuel’s ghost knifefish lives in the western Amazon of Peru and Brazil and was collected from flooded beaches and deep river channels. It can be distinguished from its close relatives by having a higher number of caudal-fin rays and a less tapering body shape in lateral profile.

Other distinctive features are the relatively short caudal peduncle and the comparatively small body size (as an adult). The mature male sports an extremely slender and elongated snout and engages in sparring with repeated aggressive non-contact postures, usually followed by jaw-locking and biting.

If you wish to learn more about Samuel’s ghost knifefish, see the paper: Albert, JS and WGR Crampton (2009) A new species of electric knifefish, genus Compsaraia (Gymnotiformes: Apteronotidae) from the Amazon River, with extreme sexual dimorphism in snout and jaw length. Systematics and Biodiversity[1] 7, pp. 81–92.

Genus: Compsaraia

New species: Compsaraia samueli

This week, Chilean president Michelle Bachelet signed into law a measure that outlaws all whale hunting in the Chilean part of the Pacific Ocean. The law prohibits all types of whale hunting; both commercial and scientific.

Whales have not been hunted off the Chilean coast for over three decades, but the government decided that a law was needed to emphasise the Chilean commitment to protect whales in Chilean territorial waters. President Bachelet says the law is “a big step ahead in the protection of nature and a major legacy to future generations.”

Several South- and Central American countries has already banned whale hunting, including Chile’s neighbour Argentina (Green on the map). Chile has a 6,435 km long coast line along the Pacific side of South America’s southernmost part, while Argentina has a 4,665 km long coastline along the corresponding Atlantic side of the continent. As you can see on the map, the new Chilean law has led to the creation of a whale sanctuary around the entire southern tip of South America. (Chile is red on the map)

Chile = Red, Argentine = Green